Contact and method for making same

ABSTRACT

A method for making a contact begins by providing a sheet of material. A portion of the sheet is deep drawn to form a cavity having at least one sidewall, the cavity extending away from a rim formed by a non-drawn portion of the sheet. At least one spring member is defined from the at least one sidewall and is bent such that at least a portion of the at least one spring member extends beyond the rim.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application No.60/554,818, filed on Mar. 19, 2004, which is incorporated by referenceas if fully set forth herein.

FIELD OF INVENTION

The present invention is related to electrical contacts. Moreparticularly, the present invention is directed to an eyelet contactwhich is suitable for use with an interposer, a printed circuit board(PCB), or the like. The present invention also includes a method formaking an eyelet contact.

BACKGROUND

There are currently many different types of connector technologies thatproduce a vast array of connectors for all different types of connectorapplications. Current connector technologies are deficient in that theyare made on a “macro-scale”, in which individual pieces of the connectorare formed separately and are then integrated together in a finalassembled contact. However, such schemes are cumbersome at best, and canresult in a defective contact when the integration does not proceed asplanned. Further, such schemes do not scale; as the pitch of contactsbecomes smaller, the problems associated with current technologiesgreatly increase. Accordingly, a new technology that avoids thedisadvantages with current technologies is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a sheet of material for making a contact inaccordance with the present invention.

FIG. 2 is a perspective view of the sheet of FIG. 1, which has been deepdrawn to form a contact having a lip and a body.

FIG. 3 is a perspective view of the contact of FIG. 2 with the bottomremoved.

FIG. 4 is a perspective view of the contact and definition of the springmember.

FIG. 5 is a perspective view of the contact showing the spring memberbeing bent above the rim of the body.

FIG. 6 is a perspective view of the contact showing the forming of thedistal end of the spring member.

FIG. 7 is a perspective view of an array of contacts made in accordancewith the teachings of the present invention.

FIG. 8 is a perspective view of an alternative embodiment of the presentinvention including a plurality of spring members.

FIG. 9 is a perspective view of an alternative embodiment of the presentinvention including additional openings.

FIG. 10 is a flow diagram of a method of forming a contact in accordancewith the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described with reference to the drawingfigures wherein like numerals represent like elements throughout. Theterms “down”, “up”, “bottom”, “side”, or “top” as used hereinafter areused only for convenience to differentiate certain aspects of thecontact in the orientation shown in the figures. It should be understoodthat these terms are not meant to limit the functional aspects of theelements to which the terms apply.

The present invention provides an eyelet contact and a method for makingthe same. The present invention may be utilized with an interposer, on aprinted circuit board (PCB), as part of another type of contact,incorporated directly into an electronic device, or may be utilized in avariety of other applications.

Referring to FIG. 1, a sheet 10 of material is shown, which is used toform a contact 8. Preferably, the sheet 10 is formed from a conductiveand resilient material such as copper (Cu) or beryllium copper (BeCu),brass, phosphorus bronze, stainless steel, or other types of laminatedor non-laminated material. Although the sheet 10 is shown as beingconfigured in a generally circular shape having a certain thickness,those of skill in the art should realize that this is for convenience ofexplanation and the shape and/or thickness of the sheet 10 will varydepending upon the particular application and the desired physicalcharacteristics of the contact. Such physical characteristics, forexample, may include the impedance of the contact, the desired normalforce to be applied by the contact, and the working range of thecontact. Other characteristics may be related to a variety of platingschemes, or contact schemes such as multiple contact members for higherpower application, contact geometry to cradle solder ball technology, orvariable heights between contacts in the array for “make first-breaklast” applications.

Referring to FIG. 2, the sheet 10 has been deep drawn to form thecontact 8 having a cavity, using a deep drawing process, leaving a lip12 at the top of a deep drawn body 14. Deep drawing is a well-knownprocess to those of skill in the metallurgical arts and, therefore, adetailed description of the process will not be set forth in detailhereinafter. Generally, however, deep drawing selectively stretches asheet of material to form a desired three-dimensional shape. Thecylindrical shape as shown in FIG. 2 and the subsequent figures is forexample only and the shape may be any shape desired for the particularapplication. For example, the body 14 may be substantially rectilinearin shape, or may be drawn deeper or shallower than shown.

The body 14 generally comprises one or more walls 16 and a bottom 18.Although the body 14 shown in the figures is substantially cylindricaland comprises a single continuous wall 16, if the body 14 is a cubic orother three-dimensional shape, there may be a plurality of sidewalls 16.Likewise, although a bottom 18 is shown, a deep drawing process may beused such that there is no bottom 18 to the body 14.

If the body 14 includes a bottom 18, the bottom 18 may optionally beremoved as shown in FIG. 3. This step is preferably used when it isdesired to have a contact 8 with an extended operating range. As such,removing the bottom 18 from the body 14 would have certain operationaladvantages, although this step is optional and is not required for thecontact 8 to operate properly.

Referring to FIG. 4, two cuts are made in the wall 16 to form a springmember 20 and an opening 22. The spring member 20 is bent away from thewall 16 and then back upon itself and in a generally vertical positionextending toward and/or through the top of the body 14 and above the lip12 as shown in FIG. 5. Although the spring member 20 is shown asextending above the lip 12, this is not required. Accordingly, thespring member 20 may also extend upward toward the opening defined bythe lip 12, but still be located below the lip 12.

Referring to FIG. 6, the distal end of the spring member 20 is then bentor otherwise formed in a desired configuration. The desiredconfiguration shown in FIG. 6 is an arch. The distal end of the springmember 20 configured in an arch forms a compliant contact area 24 formating with a corresponding contact of an electronic device or otherdevice. The corresponding contact may be a generally flat land (such asfound on a land grid array (LGA)), a pin, a solder ball (such as foundon a ball grid array (BGA)), or any other type of contact system.Although the spring member 20 is shown as bending away from the middleof the contact 8, the spring member 20 may bend toward the center of thecontact 8. Additionally, either the entire spring member 20 or thedistal end of the spring member 20 may be formed as desired to achievecertain a configuration or specific physical characteristics.

For example, it is possible to form compound springs by having onespring member, when displaced some distance, hit a lower spring memberand take advantage of the compound force that results when a firstspring member contacts a second spring member, which results indifferent spring rates.

As a further example, an angular spring member configuration typicallyurges the point of contact more forcefully into a corresponding flatland, whereas a rounded arch will glide more easily over a land. Theseconfigurations each provide distinct wiping performances.

Due to its configuration, the contact 8 shown in FIG. 6 is able toaccommodate a wide range of pin connector lengths since the bottom 18has been removed. A long mating contact, such as a pin, may be insertedinto the contact 8 without bottoming out. This provides the ability tomate with different configurations of contacts.

It should be noted that although FIGS. 1-6 were described with referenceto forming a single contact, it is envisioned that an array of contactswill be simultaneously formed as shown in FIG. 7. The individualcontacts may thereafter be singulated using either mechanical or otherknown techniques, such as photolithographic mask and etch technology.

Referring to FIG. 8, a contact 28 having two spring members 20 a, 20 bis shown. Although there is only one spring member 20 shown in FIG. 6and two spring members 20 a, 20 b shown in FIG. 8, there may be morespring members as required by the particular application. The springmembers 20 a, 20 b as configured in FIG. 8 include a large gaptherebetween, although this is not required. The spring members 20 a, 20b are configured with at least one contact area 24 a, 24 b respectively,as desired in order to properly mate with a corresponding contact.

Although the two spring members 20 a, 20 b are shown as beingsubstantially similar in length, this is not required. Asaforementioned, the particular length and shape of the spring members 20a, 20 b may change depending upon the application. In addition, it ispossible to have compound spring performance characteristics by havingone spring member, for example 20 a, with a higher profile and a secondspring member 20 b with a lower profile. Alternatively, it is possibleto provide the contact areas 24 a and 24 b extending in the samedirection, for example, with the first contact area 24 a of the firstspring member 20 a extending over and spaced apart from the secondcontact area 24 b of the second spring member 20 b so that the firstspring member 20 a, when displaced a predetermined distance, hits thesecond spring member 20 b and therefore provides a compound force thatresults when one spring member contacts another spring member. Thisprovides a different spring rate.

Although not shown, further forming operations may split the springmembers 20 into two or more contact areas 24. This would be particularlyadvantageous in an application where the multiple contact areas 24 canbe specifically tailored to the configuration of the correspondingcontact. For example, for a solder ball in a BGA, the distal ends may beconfigured to “cradle” the solder ball.

In an alternate embodiment as shown in FIG. 9, in addition to theopening 22 which is formed as part of making the spring members 20 a, 20b, a contact 38 made in accordance with this embodiment of the inventionincludes additional openings 23 to give the body 14 greater pliancy.This is particularly beneficial in an application in which the contact38 is inserted into a via (or through hole) in a PCB or other device.The extra pliancy provided by the additional openings 23 may permit thecontact 38 to be friction-fitted to a PCB or device without requiring anadditional bonding material.

Referring to FIG. 10, a method 200 for forming a contact in accordancewith the present invention is shown. The method 200 begins with deepdrawing a conductive material (step 202). The bottom of the body is thenremoved (step 204), although this step is optional. At least a portionof a sidewall of the body is slit to form at least one spring member(step 206). The spring member is then bent backward upon itself suchthat the spring member extends toward, or over, the rim of the contact(step 208). The distal end of the spring member is then shaped asdesired (step 210).

Although the present invention has been described in detail, it is to beunderstood that the invention is not limited thereto, and that variouschanges can be made therein without departing from the scope of theinvention, which is defined by the attached claims.

1. A method for making a contact, comprising the steps of: providing asheet of material; deep drawing a portion of the sheet to form a cavityextending away from a rim formed by a non-drawn portion of the sheet,the cavity having at least one sidewall; defining at least one springmember from the at least one sidewall; and bending the at least onespring member such that at least a portion of the at least one springmember extends beyond the rim.
 2. A method for making a contact,comprising the steps of: providing a sheet of material; deep drawing aportion of the sheet to form a cavity extending away from a rim formedby a non-drawn portion of the sheet, the cavity having at least onesidewall; defining at least one spring member from the at least onesidewall; bending the at least one spring member such that at least aportion of the at least one spring member extends beyond the rim; andshaping the portion of the at least one spring member to form a contactsurface.
 3. A method for making a contact, comprising the steps of:providing a sheet of material; deep drawing a portion of the sheet toform a cavity extending away from a rim formed by a non-drawn portion ofthe sheet, the cavity having at least one sidewall; defining at leastone spring member from the at least one sidewall; bending the at leastone spring member such that at least a portion of the at least onespring member extends beyond the rim; and shaping the portion of the atleast one spring member to form an arched contact surface.
 4. A methodfor making a contact, comprising the steps of: providing a sheet ofmaterial; deep drawing a portion of the sheet to form a cavity extendingaway from a rim formed by a non-drawn portion of the sheet, the cavityhaving at least one sidewall; defining at least one spring member fromthe at least one sidewall; bending the at least one spring member suchthat at least a portion of the at least one spring member extends beyondthe rim; and shaping the portion of the at least one spring member toform an angular contact surface.
 5. A method for making a contact,comprising the steps of: providing a sheet of material; deep drawing aportion of the sheet to form a cavity extending away from a rim formedby a non-drawn portion of the sheet, the cavity having at least onesidewall and a bottom; removing at least a portion of the bottom of thecavity; defining at least one spring member from the at least onesidewall; and bending the at least one spring member such that at leasta portion of the at least one spring member extends beyond the rim.
 6. Amethod for making a contact, comprising the steps of: providing a sheetof material; deep drawing a portion of the sheet to form a generallycylindrical cavity extending away from a rim formed by a non-drawnportion of the sheet, the cavity having at least one sidewall; definingat least one spring member from the at least one sidewall; and bendingthe at least one spring member such that at least a portion of the atleast one spring member extends beyond the rim.
 7. A method for making acontact, comprising the steps of: providing a sheet of material; deepdrawing a portion of the sheet to form a cavity extending away from arim formed by a non-drawn portion of the sheet, the cavity having atleast two sidewalls; defining at least one spring member from at leastone of the at least two sidewalls; and bending the at least one springmember such that at least a portion of the at least one spring memberextends beyond the rim.
 8. A method for making a contact, comprising thesteps of: providing a sheet of material; deep drawing a portion of thesheet to form a cavity extending away from a rim formed by a non-drawnportion of the sheet, the cavity having at least two sidewalls; definingat least two spring members, each of the at least two spring membersbeing defined in at least one of the at least two sidewalls; and bendingeach of the at least two spring members such that at least a portion ofeach of the at least two spring members extends beyond the rim.
 9. Acontact, comprising: a rim; a cavity extending perpendicularly away fromsaid rim, said cavity having at least one sidewall; at least one springmember formed from said at least one sidewall, said at least one springmember being bent such that at least a portion of said at least onespring member extends beyond said rim.
 10. A contact, comprising: a rim;a cavity extending perpendicularly away from said rim, said cavityhaving at least one sidewall; at least one spring member formed fromsaid at least one sidewall, said at least one spring member being bentsuch that at least a portion of said at least one spring member extendsbeyond said rim to form a contact surface.
 11. A contact, comprising: arim; a cavity extending perpendicularly away from said rim, said cavityhaving at least one sidewall; at least one spring member formed fromsaid at least one sidewall, said at least one spring member being bentsuch that at least a portion of said at least one spring member extendsbeyond said rim to form an arched contact surface.
 12. A contact,comprising: a rim; a cavity extending perpendicularly away from saidrim, said cavity having at least one sidewall; at least one springmember formed from said at least one sidewall, said at least one springmember being bent such that at least a portion of said at least onespring member extends beyond said rim to form an angled contact surface.13. A contact, comprising: a rim; a cavity extending perpendicularlyaway from said rim, said cavity having at least one sidewall and abottom, at least a portion of said cavity bottom being removed from saidcontact; at least one spring member formed from said at least onesidewall, said at least one spring member being bent such that at leasta portion of said at least one spring member extends beyond said rim toform a contact surface.
 14. A contact, comprising: a rim; a cylindricalcavity extending perpendicularly away from said rim, said cavity havingat least one sidewall; at least one spring member formed from said atleast one sidewall, said at least one spring member being bent such thatat least a portion of said at least one spring member extends beyondsaid rim to form a contact surface.
 15. A contact, comprising: a rim; acavity extending perpendicularly away from said rim, said cavity havingat least two sidewalls; at least one spring member formed from at leastone of said at least two sidewalls, said at least one spring memberbeing bent such that at least a portion of said at least one springmember extends beyond said rim to form a contact surface.
 16. A contact,comprising: a rim; a cavity extending perpendicularly away from saidrim, said cavity having at least two sidewalls; at least two springmembers, each of said at least two spring members formed in acorresponding one of said at least two sidewalls and being bent suchthat at least a portion of each of said at least two spring membersextends beyond said rim to form a contact surface.